Electric circuit interrupter



Oct. 25, 1938. H. BUCHWALD ET AL 2,134,506

ELECTRIC CIRCUIT INTERRUPTER O 1938. H. BUCHWALD Ef AL 2,134,506

ELECTRIC CIRCUIT INTERRUPTER Filed June 10, 1935 Sheets-Sheet 2 Inventors: Herbert Buchwald,

Erwin Marx,

by X l .T heir Attonneg.

Patented Oct. 25, 1938 PATENT OFFICE ELECTRIC omcorr INTERRUPTER Herbert Buchwald, Berlin-Reinickendorf, and Erwin Marx, Braunschweig, Germany, assignors to General Electric Company, a corporation of New York Application June 10,

1935, Serial No. 25,904

In Germany June 12, 1934 5 Claims.

The invention relates to electric circuit interrupters, more particularly to circuit interrupters of the gas-blast type wherein a jet of gas or fiuid from a suitable source of pressure is utilized for interrupting arcing upon opening of the circuit.

Heretofore in extinguishing the arc upon opening of the circuit by gas or a fluid such as air under pressure, the flow of gas was so adjusted that an intensive cooling of the arc was obtained. It has likewise been proposed to increase the arc extinguishing effect by locating both bases or roots of the arc at so-called arcing tips which areseparate from the contact making parts. Whatever favorable effect these arcing tips have on the interrupting capacity of the circuit interrupter is mostly attributable to the fact that they oppose, to a limited extent, the gases flowing from the actual arc chamber. This fact has,

however, not been recognized prior to the present invention.

The main object of the present invention is an improved method of circuit interruption and the correct formation of the electrode and contact structure in circuit interrupters of the aforesaid type for increasing the effectiveness of the arc interrupting gas blast.

For an understanding of the nature of this invention, consideration of the following principles is necessary.. If the are upon opening of the circuit is to be extinguished with the minimum of trouble, that is with the smallest quantity of gas at comparatively low gas pressure, care must be taken that during the arcing period and until the passage of the arc current through zero the arc develops the smallest possible amount of heat in the arc chamber. To this end it is necessary that the voltage drop across the arc be kept as small as possible during the main arcing period. The are should, therefore, notbe immoderately lengthened. Furthermore, it should be subjected only to the smallest possible transverse blast, that is, to a gas jet at right angles to the longitudinal axis of the arc. To this end it is primarily necessary that the velocity of the gas flow beyond the exhaust openings, such as in hollow or ring-shape electrodes, be reduced as rapidly and as much as possible. This cannot be effected solely by enlarging the cross-sectional flow.

For this purpose, in accordance with the present invention, a comparatively great deflection of the direction of flow is necessary. In the usual case the gas flow is through the hollow electrodes in an axial-direction. It must be deflected back in approximatelyradial direction, that is, the

concentrated jet must be completely dissipated. This result is not effected at all or in any event only to a very small extent by previously known forms of arcing tips.

In the case of these arcing tips, there is further the possibility that the points of the base of the arc will not remain at the ends of the arcing tips, but will be driven by the gas flow longitudinally along the sides thereof so that undesirable lengthening of the arc results. This possibility is likewise preventedby rapidly defleeting the gas flow in the radial direction as above described.

The invention will be more fully set forth in the following description referring to the accompanying drawings, and the features of novelty which characterize our invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawings Fig. 1 is an elevational view partly in section illustrating diagrammatically a form of our invention wherein the electrode structure is shown in the open circuit position; Fig. 1a is a similar view showing the electrode structure in the closed circuit position; Fig. 2 illustrates another form of our invention wherein the electrode structure is shown in the open circuit position; Fig. 2a is a similar view showing the electrode structure in the closed circuit position; Fig. 3 is an elevational sectional view of an electric circuit breaker of the gas blast type having incorporated therein the electrode. structure shown by Figs. 1 and 1a.

In accordance with this invention one or more deflecting bodies are positioned so as to oppose the gas flow with respect to the longitudinal axis, and are so formed that they likewise change the direction of gas flow. Furthermore, the eddies in the gas flow which cannot be avoided along the axis of the electrode arrangement and its immediate surroundings with the sharp deflection of the flow are, under certain circumstances, even made advantageous. For the purpose of deflecting the gas flow in accordance with this invention, the surface of the deflecting body opposing the gas flow may be either fiat, concave or convex in any suitable form. 1

Referring more particularly to Fig. 1, there are illustrated at the upper and lower hollow electrodes l and 2, respectively, different forms by way of example, of the above described deflecting body. The electrodes I and 2 may be fixed in spaced relation, such as in a lightning arrester, or may be relatively movable such as in circuit breakers for example. Fig. 1a illustrates the electrodes in the closed circuit position when operating as a circuit breaker.

The deflecting body 3 associated with the electrode 2 is of large diameter as compared with the passage 2' through the electrode 2. The deflecting surface at 3' may be made concave or convex in accordance with the particular design of the electrode structure.

The deflecting portion 4 which is associated with the electrode l is of slightly smaller diameter than the passage 2' in the electrode 2. The electrode I is provided with a passage l as illustrated, extending from the lower surface thereof directly in alinement with the deflecting body 4. The passage I has exhaust ports at the sides of the electrode as illustrated.

According to this invention, the diameters of the deflecting surfaces are comparatively large although the diameters should not greatly exceed the openings in the hollow electrodes. Moreover, it is necessary that the hollow electrode and deflecting body be spaced a small extent so that complete deflection of the entire cross section of the gas flow is obtained.

In the case of high voltages, however, if the deflecting body is very close to the hollow electrode, provisionmust be made for preventing reignition of the arc after extinguishing of the same by the gas flow due to the fact that parts of the electrode structure remain at high temperature for a short time. Reignition of arcing may be prevented in accordance with this invention by forming the hollow electrodes so that they function as an electric screen or shield for the deflecting surface.

The circuit interrupting operation is performed by directing gas under pressure from a suitable source between the electrodes I and 2 as indicated by the directional arrows. The gas flows axially through the passages I and 2' in opposite directions substantially parallel to and around the are between the electrodes l and 2, each jet being sharply deflected at the deflecting surfaces 4' and 3 so as to assume a substantially fan-shape flow. The direction of flow is, therefore, abruptly changed and the velocity is likewise greatly decreased radially of the base of the arc. The are which is not appreciably lengthened by this method, and therefore does not build up a great counter-pressure, is eflectively interrupted at a subsequent current zero. In the circuit breaker shown by way of example by Fig. 3, the electrode structure corresponds in form and position to that shown by Fig. 1. The fixed electrode structure 2-3 is disposed at one end of an insulating housing H, and the coacting relatively movable electrode structure i-4 is guided for vertical reciprocal movement in the opposite end wall of said housing. An insulating partition P is mounted within the housing so as to confine the flow of gas at the electrode l as previously described.

When gas under pressure is admitted as indicated, such as through laterally disposed gas supply conduits, to the intermediate part of the housing H upon separation of the contacts, the arc is interrupted in the manner previously described, the gas exhausting in opposite directions past the electrode structures as illustrated by the directional arrows. Actuation of the movable electrode structure l4 is accomplished by means of suitable operating mechanism (not shown). The fixed and movable electrode structures can be connected respectively to the external circuit terminals as diagrammatically indicated at T.

concern the most favorable The arrangement shown by Fig. 2 comprises a deflecting body 3 wherein the deflecting surface 3' is generally of conical shape extending away from the direction of gas flow. The deflecting body 4 associated with the electrode 2 in the present instance is provided with a central bore in which a movable contact rod 5 is positioned.

In the closed circuit position as shown by Fig. 2a the rod 5 is elevated so as to engage the deflecting member 3, and in the circuit opening operation the rod 5 serves as an arcing tip. It will also be apparent that the arrangement may be similar to that of Fig. 1. That is, the electrodes I and 2 may engage and the rod 5 serve as an arcing tip at the deflecting member 4. I

In the present instance the deflecting member 4 may consist of metal or insulating material, or it may be coated with an insulating material, so that the points of the arc base are limited to predetermined positions on the electrode structure. The circuit opening operation is essentially the same as that described in connection with Fig. 1, the electrode structure of Fig. 2 being particularly adapted for circuit breakers or switches of the gas blast type. However, it will be apparent that the rod-like deflecting member 4 of Fig. 1 may be movable as in Fig. 2 to bridge the electrodes l and 2.

In addition to the above described advantages, in so far as arc interruption is concerned the sharp fan-like deflection of the gas current and the change of cross-sectional flow likewise occurring result in damping of the sharp switching noise characteristic of the gas blast switch. This factor may be taken into consideration in' the design of the deflecting bodies.

In the circuit interrupting method above described, it is immaterial in principle whether one or two exhaust ports for the gas are used in the circuit interrupter, since with the selection of such a design the determining considerations ionization and removal of metallic vapors. In the case of the present invention the application of the gas flow with respect to the arc previous to the extinction of the arc is chiefly taken into account. Accordingly, a decrease for example of the gas used for extinguishing the arc and an increase of the interrupting capacity and of the voltage rating are obtained.

It should be understood that the invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art'without departing from the spirit of the invention.

What we claim as new and desire to secure by Letters Patent of the United States, is:

1. In a gas blast arc-interrupting system, the method which comprises directing gas under pressure at high velocity around and longitudinally of the axis of the arc to be interrupted in opposite directions toward both of the roots of said are, and sharply deflecting the flow of said gas adjacent said roots radially from said axis.

2. An electric circuit interrupter of the fluid blast type comprising coacting electrode structure forming a centrally disposed fluid passage, said electrode structure separable to form an arc longitudinally of said passage, means for directing a fluid under pressure into said passage at an intermediate point so as to flow longitudinally of said are without traversing and lengthening the same, and a deflecting member at one end of said passage for sharply deflecting the flow of said fluid away from and substantially radially 01' said are.

3. An electric circuit interrupter of the gas blast type comprising a pair of hollow electrodes, arcing means between which an arc may extend through said hollow electrodes, means intermediate said electrodes for directing a flow of gas through said electrodes in opposite directions so as to flow longitudinally of said are without lengtheningthe same, and deflecting means associated with each of said electrodes at points adjacent the arc roots respectively, said deflecting means being positioned at the exhaust openings of said electrodes and arranged so as to deflect sharply the flow of said gas away from and generally radially of said arc.

4. An electric circuit interrupter of the gas blast type comprising coacting electrodes, one electrode having a gas passage therethrough, said electrodes separable to form an are upon opening of the circuit within said passage, means v for directing flow of gas under pressure laterally of and into said passage and parallel to said are without substantial traversing of the arc, and a deflecting member closely spaced with respect to the exhaust opening of said electrode passage and arranged so as to deflect said flow at said exhaust away from and generally radially of said are.

5. An electric circuit interrupter of the gas blast type comprising a pair of electrodes having alined gas passages therethrough, a contact rod movable through said passages for opening and closing the circuit, means for directing flow of gas under pressure from a point intermediate said contacts through said gas passages so as to flow in opposite directions substantially parallel to an are formed upon the circuit opening movement of said contact rod, and deflecting members associated with each of said electrodes adjacent the exhaust openings of said passages for deflecting said gas away from the arc in fanlike flow.

HERBERT BUCHWALD. ERWm MARX. 

